Do employers have to tell you about promotion opportunities within your team whilst you're on maternity leave?

I went into work yesterday for a meeting as my maternity leave is coming to an end so we could plan my return. At the end of the meeting my boss told me they had recently advertised internally for a senior position within my team (by emailing all members of the team informing them of the opportunity). I really feel like I've missed out as I wasn't aware and would have liked to apply for it. Should they have told me? I know there's not really much I can do about it now, but it would help to know if they were in the wrong/right.

Oh yes they do, my last boss came to see me in hospital after the birth if my twins, at the point 1 was in SCBU and the other had been taken away as I was hooked up to a defib, still, it had been a planed visit the week before, and I had in the process of being resus forgotten to ask them to put her off

At the end of the friendly visit she exited the door then came back in, saying she had her boss head on, and that one of the nurses senior to me at resigned and the job was being advertised the next week and that whilst she was there she kept thinking, how do I let Missing know this, she is in hospital attached to a bed. She knew I was taking a year off, but she also knew my best friend had applied for a job the year before at 8 months pregnant been offered it, and the employer had to wait 10 months for her to start. So she knew I knew my rights.But also my manager was a decent human being and knew her team, on that occasion I did not apply, should have looking back, as I would have whooped the arse of the person who got the job.A year later another promotion, I was second, told that if she didn't accept then it would be me, worst 2 weeks of my life, she was on holiday, she accepted, once in post I could see why she got the job, excellent, to the point I started to doubt the fact they said I was only a point behind her.

You could either make an official complaint or perhaps advise them to be more careful in future because they could lay themselves open to a tribunal case. They can get loads of free advice from Acas if they are unsure.